Sometimes prospective clients will ask me if I specialize in their particular industry: "Do you have experience writing for the automated-widget industry?" Many times I can truthfully answer, "Yes." Other times I can just as truthfully say, "No, and here's why it doesn't matter."
So here's why it doesn't matter.
Most of us copywriters consider ourselves generalists -- professionals adept at the art of absorbing and understanding whatever information we need to write on the widest possible range of subject matter.
Specializing in a particular industry or subject has its points, of course, both for clients and for writers. Specialists usually require less intake on the subject from the client, eliminating much of the learning curve on the front end of the project. From the writer's perspective, a more specialized niche is easier to market to because that target market makes up a more cohesive group -- people who tend to belong to the same organizations and speak the same lingo.
As a generalist myself, I think general-subject writers have the edge in some notable ways. For one thing, the sheer cross-pollination of concepts, information and resources that we generalists sift through on a daily basis, year after year, enables us to see the broad view of how your particular industry relates to others. If you work in the "green" industry, for instance, your product or service may impact the manufacturing, real estate, health and wellness, energy, electronics and other industries. Well, guess what? I've written for all of those industries and many others, so I can see the connections between them -- which means that I can help your audience see them as well.
At the same time, the outsider's perspective counts for much. People who live and think in one field 24/7 start to assume that the rest of us know as much about it as they do, and they start speaking in buzzwords and technobabble without even realizing it. A writer who can step in as Joe Q. Public and say, "What's the bottom line on this stuff?" can see your products or services from a mainstream audience's point of view.
Of course, everyone specializes in some way or other. Even though I write on every topic under the sun, for instance, I focus on marketing pieces, or as I like to call it, "writing for short attention spans." The work I do has a specific mission -- to grab and hold someone who's ready to flit off to some other distraction, and then nail a point home quickly and engagingly enough that the reader makes a purchase or requests more information. But as a general-subject writer, I can do that for any industry, product or service. Generally speaking.